Are these really just an M5 self tapping screw? I assumed M6X1 but no, the pitch is obviously much too fine.

Does anyone know how deep the hole is? I have some M5 20mm LG screws left over from my GD but the parts diagram shows M5 16mm LG. I don't know what's behind there and obviously concerned since the screw is... tapping!

 

Can't you just try with a wire? I did have a look at there when installing the licence plate, and I think the next thing behind is inside upholstery panel. But that was five years ago, so not sure anymore.

BTW the screws are 5 mm tapping screws but not M5. I drilled and threaded the plastic inserts for M6 to use same screws as in front.

 

what do you mean? From what I saw on bernardi parts, the screw is M5x16, tapping. The pitch of the plastic threads in the inserts are way coarser than 1mm so M5X0.8 UNC will for sure thread even worse.

the pitch of the screws I got from the Honda parts guy looks pretty big so I’m not super confident that these will fit.

Do all metric self tapping screws have the same pitch? I can’t imagine that Honda used some exotic pitch for licence plate bolts. I’m actually surprised I’m in this situation in the first place. I don’t want to chowder my plastic inserts and have to replace them.

 

5x16 is the correct size Part #93913-15420


5x20 fender liner screws also work. They have a flat face and are anodized black

 

When I originally bought my Fit one of the first things I did was take off the plastic rear licence plate holder and throw it away because it had the dealer's name on it. I had pre-purchased from Amazon a nice chrome replacement bracket which came with matching chrome screws. I don't remember the installation but I believe the 4 new screws fit perfectly in the holes on the car and the rear bracket went on without any problems. It's still there nice and solid to this day.

 

Thanks for the responses. I went to the dealer and they hooked me up with some sweet hex head (and Phillips) M5 tapping screws. They sorta went in ok so I’m hoping the thread pitch is good. I have a white car so I find the look of steel is a cleaner look than black, which I’ve seen a lot of on Amazon.

im used to using machine screws so using a big ole self tapping in plastic seems overkill. I don’t know what Honda was thinking. At least you don’t have to worry of galvanic or crevice corrosion anymore.

 

I mean that M5 refers to cylindrical machine thread. The one you can use with a nut. https://en.m.wikipedia.org/wiki/ISO_metric_screw_thread


Rear licence plate screws are not machine thread but rather something, which I would call sheet metal screw. So it's 5x16 - not M5x16.

 

M stands for metric. 5 is the diameter 16 is the length in mm

 

Not all threads that are defined by millimeters are M threads. M threads are specifically defined in standards like that ISO below:

https://en.m.wikipedia.org/wiki/ISO_metric_screw_thread

 

M is the designation for metric screw diameter. A proper metric callout would be M#XPXL where p is the pitch in mm and l is the length in mm. Fine thread is so rare that many people write M#XL and don’t bother with the pitch since coarse is assumed.

Just look up McMaster Carr catalogs for tapping screws or the actual Honda parts diagram. M designation does not necessarily mean that it is a machine screw. I know because my old dumb self assumed that and wasted my money on M6X1 machine screws which obviously don’t matchup with the plastic threads. I’m a mechanical engineer so I work with machine screws 100% of the time. The tapping screws I know are from Home Depot and the pitch of those isn’t really designated but rather determined by if they are for wood or sheetrock or other materials. I have no idea of standard tapping screw threads.

im thinking that the threads in the inserts are not to an exact pitch. Since a tapping screw is used (in the parts catalog), maybe it is expected that the screw will cut into some of the plastic and hold in the screw.

 

I use 6x1mm machine thread bolts. Every bolt/ screw is self-tapping in those soft, plastic clips lol

 

I read the article and was amused at this tidbit:

“For example, an M6 screw has a nominal outer diameter of 6 millimetres and will therefore be a well-located, co-axial fit in a hole drilled to 6 mm diameter.”

in fact an M6 screw in a 6mm hole will simply not assemble. I challenge anyone to try. A close tolerance 6mm hole is actually 6.4mm. Wiki is still a great ressource for any engineering or math information in my opinion, but this one made me chuckle. Perhaps they were referring to an M6 tapped hole in which case the statement would be true.

 

Yes, Wikipedia is not an ensyclopedia, where everything is checked and edited before publishing.

Here in the old world M in front of a screw size always refers to a machine thread. The German Wikipedia article described it more detailed and vetter in a way how we understand it in Europe.

 

good to know! I checked some Finish wood screw catalogs and it indeed states 6xXX mm. McMaster Carr, a quintessential North American nuts and bolts supplier lists wood screws with an M designation. Seems that it’s an N-A vs Europe thing. Cheers.

 

That is defenitely good to understand for me as well. Thank you for the information.